The top emission organic light-emitting devices were fabricated on the multi-layers metal anode with co-doping method in single host system. In experiment, the multilayer Al/Mo/MoO3 anode on silicon are deposited, systematically analyzed the effect MoO3 thickness on the reflectance and found the mechanism of the MoO3 thickness variation to the reflectivity of Al/Mo/MoO3 on silicon. Experimental results showed that the luminous intensity of blue, green and red appear to change according to the current density increase, and compared with the red intensity, the luminous intensity of blue and green gradually increased. The emission in this host-guest co-doping system is considered to usually involve two emission mechanisms, energy transfer and carrier trapping, and the energy transfer and carrier trapping between the host-guest should be responsible for chromaticity coordinates shift of organic white emitting light devices. In addition, through further study, it is proved the electroluminescence intensity of dopant linearly decrease with the driving voltage applied to the device by theoretical and experimental results.